Android – Transfer data from Fragment Activity to Fragment

androidandroid-fragmentactivitybundlefragment

I'm working with a bluetooth service in my application which ables me to get received message from another device. In my FragmentActivity, i'm using a handler to get this message:

FragmentActivity:

  public final Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {

                  //my code

                  case MESSAGE_READ:
                         byte[] readBuf = (byte[]) msg.obj;
                         byte[] alpha = null;
                         alpha=readBuf;

                         if(alpha!=null){
                          //my code..
              }
        }
  }

From this Handler I would like to get a data and transfer it to a Fragment.
I tried to use bundle but it doesn't work..

The code I tried:

In FragmentActivity:

    Intent intent = new Intent();
intent.setClass(getApplicationContext(), General.class);
Bundle bundle=new Bundle();
bundle.putInt("battery", bat);
intent.putExtra("android.intent.extra.INTENT", bundle);

In Fragment:

Bundle bundle = getActivity().getIntent().getExtras();
if (bundle != null) {
int mLabel = bundle.getInt("battery", 0);
Toast.makeText(getActivity(), "tottiti: "+mLabel, Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(getActivity(), "prout", Toast.LENGTH_SHORT).show();
}

The application is returning "prout" which means that it can't get my data from my FragmentActivity.

Is there any other way to get a data frome a fragmentActivity and transfer it to a fragment?

Thank you for your help

Best Answer

Assuming that you need pass the data to the fragment at creation time, you could use setArguments() to pass data to the fragment, and getArguments() to read that data.

Bundle bundle = new Bundle();
bundle.putInt("battery", bat);
MyFragment fragment=new MyFragment();
fragment.setArguments(bundle);

FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(R.id.fragment_container,fragment);
ft.commit();

Then in onCreate() method of the fragment:

Bundle bundle=getArguments(); 
int mLabel = bundle.getInt("battery", 0);

But if the fragment is already created, then you could create a method inside the fragment that you'll use to pass data, something like this:

fragment.setBattery(bat);

Related Solutions

Android – How to save an activity state using the save instance state

You need to override onSaveInstanceState(Bundle savedInstanceState) and write the application state values you want to change to the Bundle parameter like this:

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
  super.onSaveInstanceState(savedInstanceState);
  // Save UI state changes to the savedInstanceState.
  // This bundle will be passed to onCreate if the process is
  // killed and restarted.
  savedInstanceState.putBoolean("MyBoolean", true);
  savedInstanceState.putDouble("myDouble", 1.9);
  savedInstanceState.putInt("MyInt", 1);
  savedInstanceState.putString("MyString", "Welcome back to Android");
  // etc.
}

The Bundle is essentially a way of storing a NVP ("Name-Value Pair") map, and it will get passed in to onCreate() and also onRestoreInstanceState() where you would then extract the values from activity like this:

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);
  // Restore UI state from the savedInstanceState.
  // This bundle has also been passed to onCreate.
  boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
  double myDouble = savedInstanceState.getDouble("myDouble");
  int myInt = savedInstanceState.getInt("MyInt");
  String myString = savedInstanceState.getString("MyString");
}

Or from a fragment.

@Override
public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
    super.onViewStateRestored(savedInstanceState);
    // Restore UI state from the savedInstanceState.
    // This bundle has also been passed to onCreate.
    boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
    double myDouble = savedInstanceState.getDouble("myDouble");
    int myInt = savedInstanceState.getInt("MyInt");
    String myString = savedInstanceState.getString("MyString");
}

You would usually use this technique to store instance values for your application (selections, unsaved text, etc.).

Android – Activity restart on rotation Android

Using the Application Class

Depending on what you're doing in your initialization you could consider creating a new class that extends Application and moving your initialization code into an overridden onCreate method within that class.

public class MyApplicationClass extends Application {
  @Override
  public void onCreate() {
    super.onCreate();
    // TODO Put your application initialization code here.
  }
}

The onCreate in the application class is only called when the entire application is created, so the Activity restarts on orientation or keyboard visibility changes won't trigger it.

It's good practice to expose the instance of this class as a singleton and exposing the application variables you're initializing using getters and setters.

NOTE: You'll need to specify the name of your new Application class in the manifest for it to be registered and used:

<application
    android:name="com.you.yourapp.MyApplicationClass"

Reacting to Configuration Changes [UPDATE: this is deprecated since API 13; see the recommended alternative]

As a further alternative, you can have your application listen for events that would cause a restart – like orientation and keyboard visibility changes – and handle them within your Activity.

Start by adding the android:configChanges node to your Activity's manifest node

 <activity android:name=".MyActivity"
      android:configChanges="orientation|keyboardHidden"
      android:label="@string/app_name">

or for Android 3.2 (API level 13) and newer:

<activity android:name=".MyActivity"
      android:configChanges="keyboardHidden|orientation|screenSize"
      android:label="@string/app_name">

Then within the Activity override the onConfigurationChanged method and call setContentView to force the GUI layout to be re-done in the new orientation.

@Override
public void onConfigurationChanged(Configuration newConfig) {
  super.onConfigurationChanged(newConfig);
  setContentView(R.layout.myLayout);
}

Best Answer

Related Solutions

Android – How to save an activity state using the save instance state

Android – Activity restart on rotation Android

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